Bài 3 Tìm x : a,180-2.(x-15)=$2^{3}$ . 5 b,[(6x-39):7].4=12 c,10x-$2^{3}$ .5=$10^{3}$ :$10^{2}$ GIẢI CHI TIẾT RA HỘ MIK NHA

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1. $\text{a) 180 – 2.(x – 15) = $2^3$.5.}$

   $\text{⇒ 180 – 2.(x – 15) = 8.5.}$

   $\text{⇒ 180 – 2.(x – 15) = 40.}$

   $\text{⇒ 2.(x – 15) = 180 – 40.}$

   $\text{⇒ 2.(x – 15) = 140.}$

   $\text{⇒ x – 15 = 140 ÷ 2.}$

   $\text{⇒ x – 15 = 70.}$

   $\text{⇒ x = 70 + 15.}$

   $\text{⇒ x = 85.}$

   $\text{Vậy x = 85.}$

   $\text{b) [(6x – 39) ÷ 7].4 = 12.}$

   $\text{⇒ (6x – 39) ÷ 7 = 12 ÷ 4.}$

   $\text{⇒ (6x – 39) ÷ 7 = 3.}$

   $\text{⇒ 6x – 39 = 3.7.}$

   $\text{⇒ 6x – 39 = 21.}$

   $\text{⇒ 6x = 21 + 39.}$

   $\text{⇒ 6x = 60.}$

   $\text{⇒ x = 60 ÷ 6.}$

   $\text{Vậy x = 10.}$

   $\text{c)10x – $2^3$.5 = $10^3$ ÷ $10^2$.}$

   $\text{⇒ 10x – 8.5 = 10.}$

   $\text{⇒ 10x – 40 = 10.}$

   $\text{⇒ 10x = 10 + 40.}$

   $\text{⇒ 10x = 50.}$

   $\text{⇒ x = 50 ÷ 10.}$

   $\text{Vậy x = 5.}$

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2. Đáp án:

    

   Giải thích các bước giải:

   a, $180 – 2.(x-15) = 2^{3} . 5$

   $180 – 2.(x-15) = 8.5$

   $180 – 2.(x-15)=40$

   $2.(x-15)=140$

   $x-15 = 70$

   $x=85$

   b) $[(6x-39):7].4=12$

   $(6x-39):7=3$

   $6x-39=21$

   $6x=60$

   $x=10$

   c) $10.x-2^{3}.5=10^{3}:10^{2}$

   $10.x-8.5=10$

   $10.x-40=10$

   $10.x=50$

   $x=5$

    

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